This application claims the priority of Austrian patent application No. A 1349/2001, filed Aug. 24, 2001, the subject matter of which is incorporated herein by reference.
The present invention relates, in general, to a machine for treating a track extending in a longitudinal direction and comprised of two rails fastened to ties supported on ballast, and more particularly to a machine comprising a machine frame supported for mobility on the track by undercarriages, a working unit mounted on the machine frame, and a track lifting unit vertically adjustably mounted on the machine frame, wherein the track lifting unit comprises a tool frame, lifting drives connecting the tool frame for vertical adjustment to the machine frame, flanged rollers for supporting the tool frame on each rail of the track, respectively, and two pairs of lifting rollers, mounted on the tool frame in the region of each rail, respectively, and spaced from one another in the longitudinal direction, each pair having a transverse adjustment drive for squeezing the two lifting rollers together transversely to the longitudinal direction.
The pairs of lifting rollers, acting pincer-like, are in form-fitting engagement with the rail head and roll on the underside thereof, thus enabling a continuous forward working movement of the machine during working operations. In the event of encountering obstacles or very irregular rail shapes, the two pairs of lifting rollers, positioned one following the other in the longitudinal direction, are opened one after the other and closed again after passing the problem area, thus ensuring continual engagement of the rail by at least one roller pair without interruption.
U.S. Pat. No. 4,893,565 discloses a machine which includes gripping members designed for vertical adjustment by means of a drive, thus affording the possibility of bringing gripping hooks into engagement with the rail head or, optionally, also with the rail base of the rails of the track to be lifted.
It would be desirable and advantageous to provide an improved machine of the afore-described type with which it is possible to surmount, in an easier and safer manner, regions in the track which may include areas with variations of the rail cross-section.
According to one aspect of the present invention, a machine is provided for treating a track extending in a longitudinal direction and comprised of two rails fastened to ties supported on ballast, the machine comprising a machine frame supported for mobility on the track by undercarriages; a working unit mounted on the machine frame; and a track lifting unit vertically adjustably mounted on the machine frame. The track lifting unit comprises a tool frame; lifting drives connecting the tool frame for vertical adjustment to the machine frame; flanged rollers for supporting the tool frame on each rail of the track, respectively; and two pairs of lifting rollers, mounted on the tool frame in the region of each rail, respectively, and spaced from one another in the longitudinal direction, each pair having a transverse adjustment drive for squeezing the two lifting rollers together transversely to the longitudinal direction, and a respective vertical adjustment drive for independent vertical adjustment of each pair of lifting rollers with respect to the tool frame. A spacing-apart motion of the two lifting rollers of each pair by the transverse adjustment drive is coupled to an automatic actuation of the associated vertical adjustment drive for lowering the pair of lifting rollers with respect to the tool frame.
A machine including a track lifting unit designed in this way has the advantage that the lifting rollers of a pair, temporarily spaced from one another for passing over a rail obstacle or in the event of a change in rail cross-section, can be closed again or squeezed towards one another safely and without problems immediately after passing this problem area or spot. This is of significance particularly in the case of a greater lift of the track grid, since in this case, when opening the clamp formed by the lifting roller pairs, there is an unavoidable dropping of the track grid due to its own weight, and thus a change in the rail deflection curve. This vertical shifting of the track or of the rails to be gripped is, according to the invention, compensated in a simple and highly reliable manner by the automatic lowering of the lifting rollers, so that the lifting rollers are immediately situated in the correct position again with regard to the rail head to be gripped. Since the particular attention of the operator of the machine is not required in this process due to the fact that this adjustment motion is carried out automatically, it is thus possible to avoid also any diversion and any eventual infringement of safety during working operations that might result therefrom.
According to another aspect of the invention, an actuation of the transverse adjustment drive for squeezing together both lifting rollers of a pair is coupled to an automatic actuation of the associated vertical adjustment drive for lifting the pair of lifting rollers with respect to the tool frame.
This has the advantage that, after the squeezing together of the pairs of lifting rollers behind the obstacle area, the track grid is automatically lifted back up into the previously occupied position, thus ensuring smooth and uninterrupted working progress.